1. Field of the Invention
The present invention relates generally to latching and locking devices, and more specifically to a locking mechanism providing three simultaneously actuated deadbolts from a single lock and key operation. The bolts engage the threshold, lintel, and adjacent frame or jamb at three widely separated points about the door.
2. Description of the Related Art
Conventional sliding (striker plate) latches and deadbolt latches engage the adjacent edge of the door frame or jamb, at only a single point adjacent the latch mechanism in the door. While this provides convenience and economical installation, it has become increasingly necessary to provide additional security over and above that provided by a single deadbolt or other latch bolt engaging the adjacent frame at only a single point. This is not only true for protection against unauthorized entry, but also for security against adverse weather conditions. A conventional single point latch bolt cannot provide the required strength and security in many areas of the country, where hurricanes occur on a semi-regular basis.
In these areas, very strict regulations describe the security required for a door. For example, in Florida a door must pass the test of having a length of 2.times.4 lumber propelled against the door at 34 mph, twice. The door and latch mechanism must then pass an operational cycle test.
Generally, the strength and security required cannot be met by a single deadbolt lock or latch, or even by additional pins driven into receptacles in the threshold and lintel of the door by a common lock or latch mechanism. Accordingly, such doors are required to have shutters, which adds considerably to the cost of installing and maintaining such doors. Also, the linear travel of the supplementary latch rods of existing multiple point latches or locking mechanisms, generally differ between each pin or bolt, due to the translation of motion from an arcuate direction (rotating the lock mechanism within the door) to a linear direction (to drive the bolts or pins). In addition, such bolts or pins comprising elongate rods are not particularly secure, due to the flexure which may occur in the rods, and also due to the lack of a consistent overcenter action in both directions for all bolts or pins, in order to assure that the bolts or pins will remain in the selected position.
Accordingly, a need will be seen for a three point latch mechanism which may be installed in a conventionally hinged door having a threshold, lintel, and adjacent frame or jamb. (The adjacent frame may comprise the edge of an adjacent door.) The latch bolts themselves are deadbolts having an overcenter mechanism therein, for holding the bolts in the desired retracted or extended position. A specially configured plate is secured to the central lock mechanism for the door, with a linear actuating rod extending from the plate to each of the deadbolts. The plate is specially configured to drive each of the actuating rods the same distance for a given amount of rotation of the plate. The actuating rods manipulate a lever extending from each of the deadbolts, to drive the deadbolt to an extended or retracted position, as desired. A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 4,306,432 issued on Dec. 22, 1981 to Eliezer Ravid describes a Door Lock having a series of latch bars or pins which are driven directly from a generally circular plate within the door cavity. The plate in turn is rotated by a series of levers, which in turn are actuated by a cam from a lock cylinder. A series of arcuate slots are provided in the plate, with the ends of the latch rods being secured to the slots by pins which slide in the slots as the plate is turned. Thus, the purely rotary motion of the plate is converted to purely linear motion of the latch rods. In the present mechanism, the actuating rods are not slidably affixed to the plate; the rod ends move only pivotally relative to their respective fixed locations on the plate. Also, the present invention uses the actuating rods to operate deadbolts, rather than having the actuating rods themselves serve as the bolts or pins, thus providing a much more secure mechanism.
U.S. Pat. No. 4,362,328 issued on Dec. 7, 1982 to John C. Tacheny et al. describes a Patio Door Lock having opposite upper and lower actuator rods which are selectively driven into receptacles in the threshold and lintel of the door. Each of the rods terminates in a pin which is directly affixed to the end of each rod, unlike the separate actuator rods of the present lock mechanism which actuate separate dead bolts. While the present mechanism provides the desired over center action to hold the bolts in an extended or retracted position as desired without need of springs, Tacheny et al. require springs urging the rods to a withdrawn position. Also, Tacheny et al. utilize a relatively complex linkage to drive their actuator rods, rather than a single rotary plate, as used in the present mechanism.
U.S. Pat. No. 5,077,992 issued on Jan. 7, 1992 to Frank Su describes a Door Lock Set With Simultaneously Retractable Deadbolt And Latch. The mechanism is adapted for use from the room side of a door, for a user to retract simultaneously an extended deadbolt and the conventional tapered latch bolt which engages a striker plate, by actuating a single lever. A lever driven by the latch bolt engages a slot in a cam on the deadbolt mechanism. When the deadbolt is extended and the latch bolt mechanism is actuated from inside the room, the lever is moved, thereby causing the deadbolt to be retracted also. No plural actuation rods are disclosed for driving plural deadbolts at opposite ends of the door, as provided by the present invention, nor is any rotary plate provided by Su for such actuation.
U.S. Pat. No. 5,110,164 issued on May 5, 1992 to Paul I. Whiteman et al. describes a Latching Apparatus For A Panel Door, having an upper and opposite lower rod and latch mechanism. The two rods are telescoped together from the actuating mechanism, with the upper rod being movable in rotation but not linearly, and the lower rod being linearly movable but not movable in rotation. Selective movement of the actuating mechanism and handle, actuates either the upper or the lower rod to engage or disengage its respective latch, as desired. The present mechanism drives two opposed actuating rods linearly to operate their respective deadbolts, while simultaneously operating the medial deadbolt associated with the lock or latch mechanism. No simultaneous linear actuation is disclosed by Whiteman et al.
U.S. Pat. No. 5,472,246 issued on Dec. 5, 1995 to Marino Puric describes an Independent Dual Deadbolt Locking Mechanism. The two bolts are actually only independent in that the disabling of one bolt does not affect the other bolt in the mechanism. The two deadbolts are somewhat modified from the conventional, in order to provide the desired operation. Puric uses a lever having two generally opposed arms, which rotates to operate one of the bolts with each arm. Puric also uses a spring to bias the second (upper) deadbolt toward the first deadbolt, i.e., in a retracted direction. In contrast, the present mechanism biases each of the deadbolts in the desired position (toward the extended position when extended, toward the retracted position when retracted), by means of the specific positioning of the actuators.
U.S. Pat. No. 5,498,038 issued on Mar. 12, 1996 to Ira J. Simon et al. describes a Multi-Point Door Lock System, wherein a single mechanism simultaneously drives a plurality of bolts to an extended or retracted condition. However, no deadbolts are disclosed, as used in the present invention. Rather, Simon et al. provide a series of linearly adjustable rods, with each of the rods having a latch bolt directly secured to the distal end thereof. The mechanism also requires a plurality of springs within the central mechanism, which springs are not required by the present mechanism. No overcenter action biasing the bolts (or rods) to a locked position when they are locked, or to an unlocked position when they are unlocked, is disclosed by Simon et al, as provided by the present invention.
U.S. Pat. No. 5,595,076 issued on Jan. 21, 1997 to Lee S. Weinerman et al. describes a Handle Operable Two Point Latch And Lock, wherein a central mechanism drives opposite latch pull rods to release opposite bolts in a door. The Weinerman et al. mechanism does not apply an extending action to the two opposite bolts, as is the case in the present invention. Rather, the two bolts of the Weinerman et al. device are spring biased to an extended position, and the actuating rods serve only to retract the bolts. Also, the actuating rods are secured directly to the bolts, rather than actuating a pivotal linkage to the deadbolts, as in the present invention. In addition, Weinerman et al. do not disclose any form of over center action in their mechanism, which would urge the bolts to remain in a retracted position when they are retracted.
U.S. Pat. No. 5,603,234 issued on Feb. 18, 1997 to Benjamin F. Lozier et al. describes a Multiple Lock Assembly having three locks which are selectively operable to actuate a series of bolts extending from a single bar. This mechanism is essentially opposite that of the present invention, where a single lock mechanism operates three bolts via three different linkages. The Lozier et al. mechanism is adapted for use in bank vault doors and the like, with all of the bolts being immovably affixed to a single bar, and being driven in the same direction by the movement of the single bar. No overcenter action is disclosed by Lozier et al., to urge the bolts to an extended or locked position when they are locked, and to urge them to a retracted position when unlocked, as in the present invention.
British Patent Publication No. 276,634 accepted on May 10, 1928 to Paul De Lapparent describes a Safety Fastening Device comprising a series of interengaging concentric pins in a double door. The lowermost pin of one door engages the next pin in line in the opposite door, to raise it to engage the next pin of the first door, etc., until the uppermost pin is seated in the door lintel. Thus, the two doors are securely fastened together by means of the interlocking pins, but only a single pin is securing the two doors at the lintel, unlike the multiple bolts of the present mechanism. Also, De Lapparent does not disclose any overcenter action to urge the pins to remain in an engaged position when they are engaged, and to urge them to a retracted position when they are retracted, as provided by the present invention.
Finally, British Patent Publication No. 1,563,393 published on Mar. 26, 1980 to William S. Astbury describes Door Fasteners in which a lock is provided on one side, with a latch handle on the opposite side allowing the door to be opened regardless of whether the opposite side lock is locked or not. The mechanism drives a central bolt and upper and lower rods which extend into the threshold and lintel of the door opening. However, the central bolt and the rods are direct acting, and do not activate separate deadbolts by means of pivotal actuating mechanisms at each deadbolt, as in the present invention. Moreover, Astbury does not disclose any overcenter action to urge the latch rods and pins to remain in an extended position when they are extended, and to urge them to a retracted position when they are retracted, as provided by the present invention.
None of the above inventions and patents, either singly or in combination, is seen to describe the instant invention as claimed.